Wooden casting pattern



Patented Sept. 19, 1933 1,927,076 WOODEN CASTING PATTERN Edwin WardTillotson, In, Pittsburgh, Pa., as-

signor to National Radiator Corporation, J ohnstown, Pa, a corporationof Delaware 'No Drawing. Application July 18, 1931 Serial No. 551,799

1 Claim. (01 22-158) is precipitated in situ in the interstices of thewood from the compound employed.

While I recognize it to be old in the art to employ all threeof thesemethods of waterproofing wood to ports andthe like, the invention doesnot comprise the specific manner of treatment but relies on arecognition of the peculiar adaptability of sulphur for'the protectionof wooden foundry patterns. The sulphur resists the absorption ofmoisture by the pattern, serves to protect the pattern from excessivedrying, and renders the pattern less likely to deterioration of beingstored under theconditions encountered in a foundry. At the same timethe sulphur enables the wood to be readily worked in" case the patternhas to re-shaped in any way, as its presence does not detrimentallyaffect wood-working tools.

' Because of the high melting point of the sulphur the sulphur is notsoftened when the pattern is used with molding sandat the temperaturefrequently encountered in foundries and of course no vapors or odors aregiven off from them. I r

The sulphur, moreover, discourages deterioration through the growth offungus, such as mildew, on the patterns.

It will be understood that the term patterns as used herein shall alsoinclude wooden core boxes, which of course are patterns.

I I claim:

As an article of manufacture, a wooden foundry pattern impregnated withsulphur.

This invention relates to the art of metal casting, and moreparticularly to wooden patterns and the method .of, protecting the same.

Present foundry practice requires the use of 5 woodenfoundry patternsand the cost of these patterns represents a considerable item ofinvestment. However, the wooden patterns may be needed for use only oncertain occasions. The cost of them is such that they have to be storedduring the period when they are not in use, as it would require too muchexpense to have new patterns made up for each occasion where their useis required. Under the conditions of storage, they frequently becomedamp, absorb moisture, swell, warp, and otherwise deteriorate.

According to the present invention the ordinary wooden pattern istreated to impregnate it with sulphur. The sulphur fills the pores andminute interstices in the wood and renders the pattern less susceptibleto the absorption of moisture and substantially Waterproofs it. As thustreated, the pattern is less affected either by exposure to dampness orwater or by excessive drying out.

Sulphur is a particularly desirable waterproofing material because ofits relatively high melting point and the fact that it does not causethe wood to swell when the wood is impregnated with sulphur, and doesnot volatilize. Frequently the molding sand in which the pattern isembedded v is so warm that many of the readily available waterproofingcompounds could not be used.

In carrying out my invention, the pattern may be impregnated by any oneof a number of wellknown methods. A common way of doing this is toimmerse the pattern in a bath of molten sulphur until the sulphur haspermeated the wood to the extent necessary, and the pattern then removedand the excess sulphur allowed to drip off. Various modifications ofthis process may be used according to which pressure is maintained in abath of molten sulphur, or pressure below atmospheric pressuremaintained. f

Another method for effecting the impregnation of the pattern is toimmerse it in a solution of sulphur and a solvent or into a suspensionin which the sulphur exists in a finely divided state and thereafter drythe pattern to evaporate the 5 solvent or dispersion of the medium, asthe case maybe.

Still another method comprises the immersion of the pattern into apotentially reactive sulphur compound and thereafter exposing thepattern to a reactive medium according to which sulphur EDWIN WARDTILLOTSQN, JR.

be used for poles, piles, ties, sup-

